<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <script src="../../vue.js"></script>
</head>

<body>
  <div id="app">
    <h1 :style="{opacity:opacity}">Vue真不错</h1>
    <button @click="$destroy()">销毁当前实例</button>
  </div>

  <script>
    new Vue({
      el: "#app",
      data() {
        return {
          opacity: 1,
          timer: null
        };
      },
      // mounted生命周期函数 当vue挂载完成后执行，生命周期其实也是vue的配置项
      mounted() {
        this.timer = setInterval(() => {
          console.log(1);
          this.opacity -= 0.1;
          if (this.opacity <= 0) {
            this.opacity = 1;
          }
        }, 100);
      },

      // 实例销毁也有一个生命周期函数 beforeDestroy
      beforeDestroy() {
        clearInterval(this.timer);
      },
    })
  </script>
</body>

</html>